Earlier this month, his unmistakable likeness began appearing on wanted posters across the capital; in recent days, the police have been scouring the gated apartment complex where he lives, hunting for him and other fugitive canines in a campaign that is striking fear into the hearts of otherwise law-abiding Beijingers.

“How can the government be so cruel?” said the woman who considers herself Dou Dou’s adoptive mother.

Dou Dou is among the dozens of dog breeds, including supposed miscreants like collies, Dalmatians and Labradors, that the Beijing government has long banned from much of the city. But over the last 10 days, the prohibition against such “large and vicious dogs,” as they are officially branded, has been enforced with zeal, alarming pet owners who thought the size restrictions had long since lapsed.

The police, often tipped off by cynophobic neighbors, have been carrying out nighttime raids on homes, and scores of dogs have been wrenched from the grip of their distraught owners, even those that had been legally registered with the authorities. Dog owners have been posting stories of heartbreaking encounters with the police, and a video that went viral last week shows an officer confiscating a small white dog whose owner claimed he forgot his dog license.

The police have said they are simply enforcing the long-standing ban on dogs taller than 13.7 inches in the districts that make up the heart of the capital. Big dogs, the police contend, are incompatible with city living.

With the exception of high-end pedigrees, animal rights advocates say, many of the seized animals are likely to end up in the hands of dog meat traders.

“We wish the police could find a more humane way to deal with this issue,” said Feng Dongmei, who runs the dog and cat welfare program at Animals Asia, a Hong Kong-based organization that wrote the government to plead for a change in the city’s dog regulations.